R80G/S Nasty G Box Noises - Page 2

**simmo** · #16 1 Apr 2004

Thanks Grant. It is a C3 bearing.

**bryan** · #17 5 Apr 2004

Hi Simmo,
all the ball journal bearings should be c3 spec,
the large bearing you are refering to does have a "looser" feel to it than the smaller ones , and a bit of axal float...recently rebuilt my 80g/s box so if i can help
bryan

**simmo** · #18 26 Jul 2004

Time to fix the gearbox...i will start by saying why do BMW require so many special tools? But anyway. The box is out and apart, amongst other things.

I have also noticed that a "flange" on the input shaft..if flange is the right word is also damaged. At this end this is a large washer , I assume its to stop oil flooding into the bearing, but dont know if its to fix the damaged shaft or is meant to be there.

The gearbox shifts well and I was going to replace the bearings keeping the lengths the same and not changing the location of the shims. Am I being too dodgy here?

It is refreshing to do this knowing I can give up and take it to a mechanic, and not have an expiring visa hanging over me. I'd rather do it myself though.

thanks

alec

**Grant Johnson** · #19 27 Jul 2004

Alec,

"I have also noticed that a "flange" on the input shaft..if flange is the right word is also damaged. At this end this is a large washer , I assume its to stop oil flooding into the bearing, but dont know if its to fix the damaged shaft or is meant to be there."

You'll have to be more specific on that one. Part number would help! See the links page for a link to a fiche of all the bits.

"The gearbox shifts well and I was going to replace the bearings keeping the lengths the same and not changing the location of the shims. Am I being too dodgy here?"

YES!! This is a critical adjustment and must be done right. If replacing ANY bearing the endfloat must be carefully measured and adjusted as needed. If too tight you'll toast the bearings immediately, if too loose you'll destroy the bearings later... (it's a little complicated, but true)

BMW airhead gearboxes aren't really for the backyard mechanic - I'd recommend an expert do it. It's not all that expensive or difficult - if you know the tricks and have the right tools - but you don't have the tools, measuring devices or shims.

It's possible to do a very dodgy job and it will still work - but for how long? And at what expense. When these boxes blow up it's a whole new box, and they aren't cheap.

------------------
Grant Johnson

Seek, and ye shall find.
------------------------

One world, Two wheels.
www.HorizonsUnlimited.com

**simmo** · #20 29 Jul 2004

Hi Grant

The collar on the back of the input shaft has been damaged, possibly when the gearbox crapped out in Novo after being struck by a gear. The build up on the spline end where it fits into the case suggest that this bearing should be replaced as well.
I have thrown my hands up and taken it to Phil Marshal a good BM only mechanic in Melbourne. He will put it back together properly and hopefully the gearbox will be reliable for a year or two.
The special tools start to get a bit wearing, but I have even more respect for the russians that fixed it in Novosibirsk.

So it will live after all!

**vincent danna** · #21 29 Jul 2004

alec
too bad you alreday took your gearbox apart :-)
good repair anyways

we could have recorded and compared our bearing noises

i have also same gearbox problems as before on my r100gs

maybe the "infernal triangle" gearbox-shaft-final drive is less sensible on g/s

apprently people agree on yes

if you have any comments, welcome

happy trails

http://vincent.danna.free.fr/